Well treating method and apparatus



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WELL TREATING moo AND APPARATUS Filed on. '16, 1956 9 Sheets-Sheet 9United States Patent 3,101,115 WELL TREATING METHOD AND APPARATUS MathewB. Riordan, In, La Habra, Calif., assignor to DJ Service, Inc., LongBeach, Calif., a corporation of Delaware Filed Oct. 16, 1956, Ser. No.616,223 21 Claims. (Cl. 166-42) This invention relates to the treatmentof wells and especially oil and gas wells.

In the art of drilling and completing wells, and particularly oil andgas wells, various occasions arise during which it is desirable thatfluids be injected into the well under greater or lesser pressures. Thepumping of such fluids may be desirable for the purpose of increasingthe productivity of earth formations through or into which a well hasbeen drilled, as by hydraulic fracturing. Similarly, it may be desirablefor the purpose of cleaning perforations, liners and the like in thewell, or indeed earth formation extending outwardly from the well.Again, fluid may be pumped into a well to remove water blocks or conesretarding production. It may be pumped into a well to consolidate sand,gravel and like materials adjacent the well bore. It may be pumped infor acidizing purposes. Additionally, in cementing operations cementslurry is pumped into wells for the purpose of anchoring casing, for thepurpose of isolating various zones of the well and the like.

in these operations it is frequently necessary to obtain high fluidvelocity rates, i.e., injection rates, or high pressures, the additionof considerable energy to the fluid sys tem being consequently required.Thus, for example, in hydraulic well fracturing wherein oils or otherfluids of varying characteristics are pumped into the well and from thewell out into the formation for the purpose of fissuring or fracturingthe formation to increase its permeability and hence its ability toproduce oil, commercial experience has shown that oftentimes pressuresextremely diflicult to obtain become necessary. Similarly, commercialexperience has established the value of high injection rates in thistype of operation. In order to obtain the necessary pressures and/ orthe desired injection rates pumping equipment at the surface capable ofdelivering large amounts of energy to the fluid being pumped isrequired. Since the fracturing fluid must be pumped from wellhead towell bottom through casing or tubing, as the case might be, frictionlosses are involved which pose formidable problems, becoming ultimatelyinsurmountable, even despite the willingness of the operator to providevirtually unlimited pumping capacity at the well site. The difficulty'ispresent in greater or lesser degree in all the above mentionedoperations, and such difliculty is two-fold, it being both an economicdifliculty, and given the necessity of sufficiently high injectionrates, a problem physically impossible of solution.

It is with this general problem that the instant invention is concerned,and the invention basically contemplates a means whereby added energy asa supplement to the energy available from the pumps may be imparted tothe fluid injected into the well to increase fluid injection rates,pressure, or both. In this the invention contemplates a method where-bythe aforesaid problem of frictional losses may be eliminated in allsubstantial respects so far as is concerned the added energy whichsupplements the energy afforded by the pumping units. This isaccomplished through the use of a gas generating means placed adjacentthe point of egress of the fluid from tubing or well casing, the energysupplied by the gas sharply increasing the fluid flow rate and/orpressure, and at the same time avoiding friction loss for the reasonthat the fluid in advance of the gas is not the fluid that must passfrom wellhead to egress point through substantial distances of pipe.

It is the basic object of the instant invention, therefore, to addenergy to the fluid system involving a well into which fluid is beingpumped, independently of the pumps.

It is a further object of this invention to add such energy in thevicinity of the point of fluid egress from casing, tubing or pipe toeliminateloss of such energy due to friction derived therefrom.

Similarly, it is a general object of this invention to provide a novelmethod and means whereby an energy source may be located in a welladjacent the site of an operation and activated to develop energy in theform of fluid horsepower to supplement the energy being delivered to thewell through the surface pumping of the fluid.

Another object of the invention is to provide a combined method ofdisplacing fluid in a well at high injection rates whereby a giveninjection rate is effected by one source, and during one or moreselected time intervals an auxiliary or booster source is coupled to themoving body of fluid to effect for a relatively short time a highincrement of added injection rate.

Yet another object of this inventionis to provide a novel method andmeans for abruptly increasing the rate of injection of fluid within awell during the pumping of the fluid downwardly from the ground surface.

Yet a further object of the invention is to provide a novel method andmeans whereby gas under high pressure may be introduced'into a movingbody of fluid within a well to increase the injection rate and, hence,the pressure of said fluid.

And a still further object of the invention is to provide a novel methodand means whereby the addition of such gas may be controlled by the rateof pumping from the ground surface.

Other objects and advantages of the invention will become apparent fromthe following detailed description, reference being bad to theaccompanying drawings, wherein: I

FIGURE 1 is a fragmentary view and side elevation illustrating, in partschematically, one form of wellhead equipment for use in carrying outthe method of this invention;

FIGURE 2 is a longitudinal sectional view of the lower portion of thewell shown in FIGURE 1 and includes bottom hole equipment used incarrying out the aforesaid method;

FIGURE 3 is an enlarged longitudinal sectional view of the gas generatorshown generally in FIGURE 2;

FIGURE 4 is a transverse sectional view taken on line 44. of FIGURE 3;

FIGURE 5 is a view similar to that of FIGURE 1 showing another form ofapparatus for use in carrying out the method of the invention;

FIGURE 6 is a view similar to FIGURE 2 showing the lower portion of thewell of FIGURE 5 including therein the apparatus;

FIGURE 7 is a transverse sectional view taken on line 7--7 of FIGURE 5;

FIGURE 8 is a view in side elevation, with parts broken away, of theaforesaid modified apparatus;

FIGURE 9 is an enlarged longitudinal sectional view of the upper portionof the apparatus of FIGURE 5, showing the parts in initial position withrespect to operation;

FIGURE 10 is a downward continuation of FIGURE 9;

FIGURES ll, 12 and 13 are transverse sectional views taken respectivelyon lines 11-11, -l212, 13-13 of FIGURE 10;

FIGURE 14 is a view similar to FIGURE 9 but showing the parts in anintermediate stage of operation;

FIGURES 15, 16 and 17 are transverse sectional views 3 takenrespectively on lines 15, 16 and 17 of FIGURE 14;

FIGURE 18 is a view similar to FIGURES 9 and 14 but showing the parts ina subsequent position;

FIGURE 19 is a downward continuation of FIGURE 18 and shows the lowerend of the apparatus;

FIGURE 20 is a transverse sectional view taken on line 20--20 of FIGURE19; and

FIGURES 21 to 25 are schematic views illustrating successive relativepositions of the cam mechanism showing in FIGURES 9 and 14.

As stated hereinabove, the instant invention generally comprises amethod and apparatus for conducting the method whereby a gas generatingpropellant is positioned adjacent the egress point for the well fluid inthe well bore and the injection rate and/or pressure of said fluid increased through the generation of gas by said propellant whereby energyis added to that afforded by the surface pumping units and used toimpart to the fluid in the system the increased injection rates andpressures.

Referring now to the drawings, and particularly to FIG- URES l and 2,whereby a particular utilization of the method and a particularembodiment of the apparatus is shown, a well generally designated 30 isshown drilled into a producing or potentially producing formation 32,and well casing 34 extending to a level adjacent the upper boundary ofthe formation 32 has been cemented in place. A string of well tubing 36is suspended in the well by conventional wellhead equipment indicatedschematically at 38 with the lower end of the tubing extending below thelower end of the casing 34, the tubing having a bull plug or otherclosure member 40 at its lower end, the said lower end of the tubingbeing slotted as at 42 and being connected to the tubing string by astop collar 44 provided with a restricting seat 46 of lesser innerdiameter than the inner diameter of the said tubing. Packing off of thetubing 36 against'the casing 34' is indicated at 45. Conventionally,hold down slips, not shown, may be used in asso ciation with the packer.

The tubing string at the surface is provided with a wellhead lubricatorgenerally designated 48, to which is connected a valve manifold,generally designated 50. The valve manifold comprises the conduit 52which is split by the T 54 into two conduits 56 and 58, the latter beingprovided respectively with the valves 60 and 62 and connectingrespectively with the lubricator chamber 64 and tubing 36. Thelubricator chamber 64 is itself provided with a trap or insertable pinassembly 66 which releasably supports the propellant canister 68 to behereinafter described, and the chamber is connected through a hingedunion 70 to the tubing 36 whereby the said chamber may be pivoted awayfrom the tubing to permit insertion of the canister 68. Shown on thetubing 36 is the master gate valve 72.

Referring now to FIGURES 3 and 4 wherein the canister 68 is shown indetail, such canister comprises a housing or shell 74 closed by an upperplug 76 affixed to the shell by shear pins 78 and closed by lower plug80 affixed to the shell by the shear pins 82, the plug 80 having ports'84 and supporting shear disk 86.

The interior of the canister is divided into two compartments by theslidable sealing cup 88, which sealing cup is'provided with a port 90against which seats a ball check valve 92 permitting fluid flow onlydownwardly through the canister. The upper compartment of the canisteris filled with a fluid 94 and the lower compartment with a material 96adapted to react with or catalyze the fluid 94 to provide generation ofgas. Various gas generating reactions, catalytic or otherwise, are well-.kIlOWIl. In the illustrated embodiment of the invention the fluid 94may comprise a mono-propellant such as hydrogen peroxide, H As islikewise welbknown, hydrogen peroxide decomposes by reaction orcatalysis in the presence of various organic or inorganic material toproduce quantities of gas. In the illustrated embodiment the material 96may comprise an inorganic catalyst which promotes the decomposition ofthe hydrogen peroxide. Available catalysts for this phenomenon arewidely known, such as lead, iron, copper, silver, cobalt, carbon andmanganese. The catalyst may have varying physical forms as, for example,iron screen alone or screen suitably coated with silver, copper,manganese, cobalt or the like. The catalyst may likewise be in the formof impregnated porous stones or indeed mere particles of the aforesaidsubstances. It has been found desirable that the catalyst particles begraded from fine particles in the upper portions of the compartment tocoarser particles in the lower portions to avoid the blowing out ofunused catalyst through the ports 84. As is apparent, it is the purposeof the propellant canister to permit the fluid 94 upon the exercise ofsuitable pressure, to flow through the check valve 92, and through'thecatalytic or reacting material 96, whereupon gas is generated whichbursts the shear disk 86 and flows through the ports 84.

In operation of this form of the invention which is described inconnection with a hydraulic we'll fracturing operation, the lubricatorchamber 64 is pivoted by the union 70 and the trap 66 opened to permitthe insertion of the canister 68, whereupon the trap is closed and thelubricator 64 pivoted back to its vertically closed position. With themaster gate valve 72 and valve 60 closed and the valve 62 open thefracturing operation is proceeded with in conventional manner, fluidsuch as jelled hydrocarbon, crude oil or other liquid being pumped bythe surface pumps through the conduit 52 down the tubing 36, out of theslots 42 and into the formation 32. It is the purpose of the fracturingoperation, of course, to fissure the formation 32 and in the. usual caseto introduce sand carried by the fluid being pumped into the formationitself into the fissures to retain those fissures propped open so thatproductivity of the formation may be enhanced.

Since the nature of various formations will generally vary widely,different conditions will be encountered. Frequently, extremely highpressures will be necessary in order to accomplish the fracturing of theformation. On the other hand, relatively permeable formations may beencountered in which case effective fracturing pressures are difficultof attainment, due simply to fluid loss into the formation. Afterfracturing it is desirable to introduce as much sand as is possible intothe fissures in the formation, and suflicient flow rates must becontinuously maintained so that the sand may be retained suspended inthe fluid lest it be dropped within the well bore to requite a shuttingdown of operations and a bailing out of the well. It will be apparent,therefore, that continuous high flow rates are important and indeedessential to successful fracturing and that higher flow rates produceoptimum results. As aforesaid, however, continuous flow rates havedepended upon the energy delivered to the system by the surface pumps,and the long lengths of tubing 36, usually many thousands of feet,render inevitable friction losses. As injection rates increase,regardless of the willingness of the operator to incur high expense inadditional pumping equipment, these friction losses becomeinsurmountable. Indeed, the point is rapidly reached where as injectionrate at the surface is gradually increased friction losses rise untilneither bottom hole pressures nor bottom hole flow rates may be furtherin- 1greased lest the tubing adjacent the surface of the well be urst.

Accordingly, the instant invention is utilized and energy is added tothe system in the vicinity of the actual treating operation to increaseflow rate and/or pressure while neither interrupting the continuousdelivery of energy to the system by the surface pumps not losing anysubstantial amount of the added energy to friction.

Without stopping the pumps the valves 60 and 72 are opened. The trap 66is then opened, permitting the descent of the canister 68. It is notedthat an hydraulic pin such as that shown'in FIGURE 7 of the drawings andsubsequently described may be used in place of the trap 66. The valve 62may be closed to assist descent of the canister into the tubing ifnecessary. The canister 68 then progresses down the tubing due to thecontinuous pumping of the fluid through the manifold 50 until it reachesthe position shown in FIGURE [2, it then being checked by the collarseat 46. Fluid pressure immediately becomes effective on the upper plug76 within the canister 68 to shear the pins 78. The plug drives thehydrogen peroxide 94 through the ball check valve 92 and it passesthrough the catalyst 96, the said catalyst causing its progressivedecomposition into gas. The gas thus produced bursts the shear disk 86and rushes through the ports 84 and out the ports 42 in the tubing 36,driving, of course, the fluid below the canister and the fluid which haspreviously been pumped against and into the formation 32 before it attremendously increased injection rates, thereby incrementing the energyin the system.

Due to the movement of the upper plug 76 the hydrogen peroxide will, ofcourse, gradually all be forced through the valve 92 and the catalyst 96and hence will be decomposed. When the plug 76 reaches the sealing cup88 both continue to move downwardly and the force imposed upon the shearpins 82 by these members, by the catalyst 96 and by the lower plug 80causes shearing of the said pins. Thereafter the upper plug 76, thesealing cup 88 and its associated ball check valve 92, the catalyst 96,the shear disk 86 and the lower plug 80 all pass through the tubing 36,coming to rest below the ports 42 within the lower extremity of saidtubing. The valve 62 may then be opened, the valves 60 and 72 closed andthe fracturing operation continued in conventional manner. As will havebeen observed, the immediately described valving arrangement could havebeen utilized as soon as the canister passed the main gate valve duringits descent into the tubing.

It is notable that in the above operation decomposition of the fluidpropellant and consequent gas formation takes place over a relativelylong period of time, preferably on the order of about ten seconds, itbeing necessary to avoid sharp pressure peaks such as would beoccasioned by the use of detonating explosives and the like. On theother hand, the inherent nature of the invention enables relativelysimple control of gas production and consequently of the time intervalduring which the additional energy is imparted to the system. Inaddition to the obvious control available through the use of differentfluids and catalysts, the rate of passage of the fluid 94 through thecatalyst 96 is a function of the pumping rate at the surface and, thus,relatively rapid or relatively slow gas generation may be readilyachieved.

After the incrementing of the energy to the system through utilizationof the instant invention, the conventional well treatment, such as inthis case fracturing, may proceed. It may, however, be desirable thatadditional increments of energy be added. Another canister 68 isinserted into the lubricator 64 and pumped down to seat upon the housingor shell 74 of the previously used canister, which housing or shell, ofcourse, has remained seated upon the collar seat 46. When the secondcanister reaches its seated position the continuing fluid pressureafforded by the surface pumps causes gas generation and the delivery ofa second increment of energy to the system, after which the plugs,valving and the like within the second canister are deposited at thebottom of the tubing, leaving the shell of the second canister seated onthe shell of the first. As will 'be apparent, the nature of theapparatus permits a plurality of canisters to be used in similar manner.

Referring now to FIGURES 5 through 25, inclusive, of the drawings, thereis shown alternate apparatus for carrying out the method of the instantinvention, the apparatus itself being claimed in copending applicationSerial No. 120,872, filed June 19, 1961, as a continuation ofapplication Serial No. 616,333, filed concurrently herewith in the namesof Lyle B. Scott and Mathew B. Riordan, Jr. In FIGURES 5 and 6 as inFIGURES l. and 2 the well 30 is drilled into the formation 32 and thewell casing 34 cemented in place, the string of tubing 36 beingsuspended within the well by conventional wellhead equipment 38 andhaving the bull plug or other closure member 40 at its lower end. Again,the lower end of the tubing is slotted as at 42 land the tubing ispacked as at 45. In association with the packer may be conventionalhold-down slips not shown.

At the surface connected to tubing string 36 by a collar 98 is a valvemanifold generally designated 100. The valve manifold comprises theconduit 52 which is split by the T 54 into two conduits 56 and 58, thelatter being provided respectively with the valves 60 and 62 andconnecting respectively with the manifold body 102 at its upper andlower portions.

As distinguished from the apparatus formerly shown, no gas generatingcanister is insertable within the manifold 102. On the contrary, a gasgenerator 106 with associated firing head 108 is made up in the stringof tubing adjacent its lower end, such gas generating tool beingconnected at its upper extremity to the tubing 36 through the adapter110 and at its lower extremity to the said tubing by a collar 112. Thegas generator is fired by the dropping of the plug 114, which is shownin FIG- URE 5, within the manifold 102, such plug being retained withinthe manifold by a hydraulic pin 116.

The hydraulic pin 116, which is shown in FIGURE 7, functions to providean improved means for dropping the plug 114 without releasing systempressure, i.e., without requiring the stopping of the surface pumps. Itconstitutes a cylindrical pin body 118 threaded into the manifold body102, the pin body being bored at 119 to receive a piston 120 slidable insaid bore from which piston extends the pin 122 slidable in thediminished bore 123 of the said pin body. The outer extremity of the pinbody is counter bored as at 124 and thread-ably receives the nut 126from which extends into the bore 119 the plug portion 128. The nut 126shoulders on the head 130.

O-rings 132 and 134 are provided to seal respectively at the piston 120and plug 124 and O-ring 136 provides a seal between the pin body and thepin 122. A passaige 138 is provided through the pin 122 and piston '120an a similar passage 140 is provided through the plug 128, the saidpassage 140 being extended through the nut 126 by the counterbore 142. Ascrew valve 144 threads into the counterbore 142 seating against thepassage 140.

Since the cross-sectional area of the piston 120 exceeds that of the pin122, it is readily seen that the foregoing assembly provides adifferential area piston. So long as the screw valve 144 remains closed,fluid pressure within the manifold 100 retains the pin 122 in its closedposition across the manifold to retain the plug 114 within the manifold.Release of the screw valve 144 permits pressure to bleed away from theouter side of the piston 120 whereby fluid pressure forces the pin 122from its closed position permitting the plug 114 to drop from themanifold 102. Subsequent closing of the screw 144 causes a fluidpressure buildup on the outer face of the piston 120 which returns thepin to its closed position. For the purpose of by-passing the plug 114 apassage 146 having ports 148 and 150 is provided in the manifold 102. Aunion or cap 152 is threaded to the upper manifold body 102.

Referring now to the firing head 108, as previously stated it isconnected to the tubing string 36 by an adapter 110, the said adapterbeing threaded into the firing head body 154 which itself is encompassedby a firing head case 156 sealed at its lower extremity to said body byan O-ring 158 and at its upper extremity by an O-ring 160, there being aring 162 interposed between body and case. A nut 163 threads on thefiring head body 154 to retain the case in place. A gas generator casing164 is sealed with respect to the firing head body 154 by O-rings 166,an orifice tube 168 within said gas generator case being threaded intothe lower extremity of the firing head body. As shown in FIGURE 19, abushing 169 is welded to the orifice tube and a ring 171 welded to thegas generator casing 164 and interposed between bushing and casing.

O-ri'ng 173 provides a seal, and the nut =175 threaded on to the bushingholds the casing in place.

As will be hereinafter described, the gas generator 106 carries a slowburning propellant, which upon being fired, generates thegaswithin thesystem, thus imparting the additional energy thereto. Firing isaccomplished by the firing head 108. Slidable within said firing head inthe firing head body 154 and sealed with respect thereto by the O-rings170 is an innersleeve 172, the inner sleeve 172 carrying drive lugs 174.The drive lugs 174 are adapted to slide within the slots 176 of thefiring head body 154 and themselves are affixed as by the screws 178 toa firing cam 180 which is rotatable on the firing head body and includesthe cam surfaces 182 and 184. These cam surfaces are adapted to coactwith the pin followers 186 and 188, which pin followers are integralwith and project inwardly from an annular hammer 190, a spring 192 beinginterposed between the annular hammer and the firing cam to cause thehammer to strike the firing pins 194 to fire the percussion cap 196 inmanner to be hereinafter described. The firing pins 194 are slidablysupported by a breech block 198 carried by the firing head body 154, afiller plug 199 being also supported by the firing head body and affixedthereto by the screws 201.

L-slots 200 coacting with pins 202 projecting from the firing head body154 control descent of the hammer 190.

Firing of the cap 196, as previously stated, is accomplished by thehammer 190 which descends through action of the spring 192, FIGURE 9 ofthe drawings showing the firing head mechanism prior to firing, FIG- URE14 showing the mechanism about to fire and FIG URE 18 showing it, inpart, after firing. FIGURES 21 through 25 diagrammatically show theaction between the firing cam 180 and its cam surfaces 182 and 184 andthe hammer 190 and its pin followers 186 and 188. When the hydraulic pin116 is caused to permit the plug 114 to drop down through the tubing itcomes to rest within the inner sleeve 172 as shown in FIGURE 14, thesaid plug being of resilient composition such as rubber and of suchdimensions as to be wedgeable within the said inner sleeve in tightfrictional fit. Fluid pressure afforded by the surface pumps thenimparts through the plug 114 a downward force to the inner sleeve, whichthrough the drive lugs 174 urges the firing earn 180 downwardly againstthe spring 192. This drops the firing cam 180 from its position shown inFIGURES 9 and 21 to the position shown in FIGURES 14 and 22 and pinfollower 186 is caused to ride along the cam surface 182, therebyrotating the hammer 190. Rotation of the hammer 190 moves the pins 202from the closed portions of the L slots 200' towards the open portionsthereof as shown in FIGURE 23 until the hammer is free to descendsharply under the urging of the spring 192. This is shown in FIGURE 24and the result whereby the said hammer drives the pins 194 into the caps196 to fire same is shown in FIGURE 18. Firing of the caps 196 of coursesets off the propellant within the gas generator 106 in manner to behereinafter described.

During the aforesaid operation of the tool, the plug 114, after thesleeve 172 has reached the end of its travel is caused by fluid pressureto be expelled from the sleeve and to be deposited in the lowerextremity of the tubing 36. Recocking of the tool at the surface isshown in FIGURE 25, movement back of the firing cam 180 with respect tothe hammer 190 and against the spring 192 causing the pin 188 to ride onthe cam surface 184, thereby rotating back the said hammer until thepins 202 are disposed within the closed portions of the L slots 200. Thetool is then cocked for firing and in the position shown in FIGURE 9.

Referring now to the gas generator 106, it has already Y 8 been notedthat the gas generator casing 164 is sealed with respect to the firinghead body 154 by O-ri-ngs 166 and with respect to the orifice tube 168by the O-ring 173 to provide an annulus 208, in which annulus is placedthe gas generating propellant.

The gas generating propellant used is a slow burning propellantrequiring on the order of 10 seconds to burn completely and is shown insplit ring form as the propellant 210. While the gas generator is shownforeshortened in the drawings, it may consist of considerable lengthsuch as, for example, 15 feet in comparison with a length of about 2feet for the firing head. Thus, a number of split rings of propellant210 may be utilized. The propellant itself may be one diverse so-calledslow burning propellants such as rubberized ammonium nitrate and thelike. Such a solid propellant may be obtained, for example, from GrandCentral Rocket Company in Mentone, California, under their designationsCBS- 128K or CBS-128H. It may comprise ordinary railroad fuseesmaterial, such as sawdust impregnated with sodium or ammonium nitrate,or it may comprise one of a variety of rocket fuels. Suitablepropellants are described in Chemistry of Powder and Explosives, 1943,by T. L. Davis, John Wiley and Son. As is well-known, these solidpropellants may be adjusted in composition to burn at varying rates, butas stated, about 10 seconds is preferable when used with the instantinvention.

In order to insure firing of the propellant, as a result of firing ofthe caps 196, additional propellant 212 and 214 is used to form a firingtrain to the main bodies of propellant 210 and although varyingarrangements within the skill of those trained in the art may be availedof, in the instant embodiment of the propellant 212 is shown in stripform glued to the firing head body 154 terminus adjacent the caps 196.The propellant 214 is shown interposed between the aforesaid strips andthe mai body of propellant in strip form but glued to the orifice tube168 and somewhat thicker, providing therefor a propellant train ofgradually decreasing surface area relative to propellant volume.

Prior to the firing of the herein described tool the orifice tube 168 issubjected to the pressure of the fluid being pumped into the formationthrough the tubing 36. The annulus 208 is therefore sealed from suchfluid, but to provide means whereby the gas generated by the propellant210 may enter the orifice tube and hence the tubing, sealing ports 216are provided in the orifice tube. These tubing ports 216 are sealed bythe plugs 218 and provided with the bores 220 sealed by the sealingdisks 222, the said plugs being threaded into the rings 224 welded tothe orifice tubes. 0 rings 226 provide a seal between the rings 224 andplugs 218. Since the sealing disks seat upon shoulders facing inwardly,the aforesaid plug arrangement provides an effective means to preventfluid egress from the ports but permits upon burning of the propellant210 the issuance of gas into the orifice tube, the sealing disks 222being, of course, blown from the plugs 218 by the gas.

The method of the instant invention is conducted using the instantapparatus just as in the case of the previously described apparatus and,as with the previously described apparatus, this apparatus is used toincrement the energy added to the fluid being pumped into the well bythe surface pumps. The tool, however, is run into the well as part ofthe tubing string. Before the job starts the plug 114 is placed withinthe upper portion of the manifold body 102 by removing the cap 152 andheld suspended therein by the hydraulic pin 116 which is in its closed,i.e., extended, position. With the valve 60 closed and the valve 62opened, the pumping operation is proceeded with in the usual mannerutilizing the surface pumps, the passage 146 affording opportunity forthe fluid pressures upon the plug 114 to balance. When it is desired toincrement the energy in the system the screw valve 144 is opened,permitting opening of the hydraulic pin 116, the valve 60 being openedand the valve 62 closed. Since the surface pumps continue to run thiscauses the plug 114 to be pumped down through the tubing until itreaches the inner sleeve 172 through which it is pumped. Frictionbetween the plug and the sleeve 172, however, causes the said sleeve tomove downwardly with respect to the firing head body 154, causing, aspreviously described, the firing pins 194 to be driven into the caps196, whereupon flame from the said caps ignites the propellant train,gas is generated within the annulus 20 and the said gas bursts throughthe ports 216 passing th ough the tubing and driving the fluid before itinto the formation.

As distinguishedfrom the first described apparatus, it is not possibleto reuse the instant apparatus in situ to add a plurality of incrementsof energy to the fluid being pumped. On the contrary, the tubing must bepulled from the well and new propellant providing about the orificetube. This is readily accomplished by the unthreading of the nut 175 andthe slidin off the gas generator casing 164. Recocking of the firinghead 108 is made possible by the unthreading of the nut 163 and thesliding off of the firing head case 156.

To provide an example of the carrying out of the method on an actualwell, General Petroleum Tonner No. 23 in the Brea Olida field wasfractured and the instant invention utilized in such fracturing. Casinghad been set in the well and terminated by a slotted liner hung from2730 ft. to 3139 ft., the liner being perforated from 2795 ft. to 3139ft. Tubing was run down into the well terminated by a perforated tailpipe acting both as a plug catcher and to carry a subsurface pressurerecorder. Above the perforated tail pipe was provided a packer and slipassembly for packing off the annulus between tubing and casing andanchoring the tubing. The packer assembly was positioned at 2710 ft.Immediately above the packer was the apparatus shown in FIGURES through25 of the drawings and above that apparatus the tubing string. Theposition of the apparatus was therefore approximately 85 ft. from theperforations. Pressure gauges were provided for the tubing at thesurface and at the pump truck.

The tubing and annulus were first filled with lease crude oil afterwhich fracturing operations commenced. 20 barrels of the crude oil werepumped down the tubing at a rate of 6 barrels per minute, the bottomhole pressure, the tubing pressure and the pump truck pressure allgradually rising until during the pumping of said 20 barrels of oilbreakdown pressure was achieved. Such pressure was recorded as 2500p.s.i. at the bottom of the well, approximately 2000 p.s.i. in thetubing at the surface of the well and approximately 2500 p.s.i. at thetruck.

After the displacing of the aforesaid 20 barrels of oil, but withoutstopping the pump truck and continuing the pumping rate of 6 barrels perminute the plug 114 was permitted to descend in the tubing. When theplug reached the firing head 108 the apparatus. fired and the propellantin the gas generator 106 generated gas to provide the desired additionalenergy to the system. During and after the travel of the plug 114 to thefiring head and the operation of the tool, additional oil was pumpedinto the tubing all at a rate of 6 barrels per minute. Thus pumping atthe 6 barrel per minute rate was continuous from the commencement of thefracturing job until after the operation of the tool. Pressure gaugesshowed that when the tool fired, pressure at the bottom of the well roseto 3100 p.s.i., at the surface in the tubing to 2950 p.s.i. and at thepump truck to 3400 p.s.i. The tubing was then pulled and the toolprepared for further use. No damage appeared to be occasioned to eitherthe tool, the wellhead equipment or the subsurface equipment.

The solid propellant used in the tool in the aforesaid conducting of themethod of the invention had a burning rate of .098 inch per second.Subsequently, and on the following day, the same well was subjected tothe same treatment, using, however, a solid propellant having a burningrate of .135 inch per second. The same procedure was followed but firingof the tool and consequent gas generation caused higher pressuresbecause of the faster burning rate of the propellant. Bottom holepressure Was indicated to be 4150 p.s.i. Pressure in the tubing at thesurface was 3300 p.s.i., and pump truck pressure 3900 p.s.i. Again whenthe tubing was pulled no dam-age was evident as concerns either surfaceor subsurface equipment.

The foregoing establishes the effectiveness of the instant method inaffording a very substantial increment of energy available for additionto the energy provided by the pumping trucks in an hydraulic pumpingoperation. On the first day the addition of this energy was evidenced bya bottom hole pressure rise of 600 p.s.i., by a tubing pressure rise ofapproximately 1000 p.s.i. and by a pump truck pressure rise of about 900p.s.i. On the second day the pressure differentials were respectivelyabout 1600 p.s.i., 900 p.s.i. and 1500 p.s.i. These pressure risescaused by the operation of the tool required no shutting down of surfacepump operations. On the contrary, the surface pumps maintained a fluidflow rate of 6 barrels per minute continuously during the operations.

While the instant invention has been described particularly inconnection with fracturing operations, its utility is manifest whereverit is desired to increase flow rates and/or pressures when pumpingfluids into wells. As previously indicated, this operation is involvedin many types of well treatments. Consequently, the invention is deemedto include that which is defined by the full scope of the followingclaims.

I claim:

1. The method of introducing fluid under pressure into earth formationinto or through which a well has been drilled comprising: pumping fluidthrough the well into said formation from the earth surf-ace; disposinga material below said surface and adjacent said formation capable of gasgeneration within the well; and inducing the generation of gas by saidmaterial responsive to and during said surface pumping to increase thepressure acting on the fluid and force the same into said earthformation.

2. The method of introducing fluid under pressure into earth formationinto or through which a well has been drilled comprising: pumping fluidthrough the well into said formation from the earth surf-ace; disposinga second fluid below said surface and adjacent said formation capable ofgas generation within the 'well; inducing by the pumping of fluid thegeneration of gas by said second fluid during said surface pumping, andimplementing the rate of injection of fluid into said earth formationwith said gas.

3. The method of introducing fluid under pressure into earth formationinto or through which a well has been drilled comprising: pumping fluidthrough the well into said formation from the earth surface; whilepumping introducing within said well a second fluid and a materialwithin the well adjacent said second fluid capable upon contacttherewith to cause said second fluid to generate gas within said well;continuing such surface pumping to cause contact between said secondfluid and said material responsive to and during said pumping togenerate gas and implementing the rate of injection of fluid into saidearth formation with said gas.

4. Fluid injection apparatus for a well comprising: surface pumpingmeans for pumping fluid into said well; a compartmented containeradapted to be lowered in said well in said fluid; a gas gene-ratingfluid within a first compartment of said container; a material in asecond compartment of said container capable upon contact with said gasgenerating fluid of causing said gas generating fluid to generate gaswithin said well; means for arresting movement of said containerdownwardly in said well and means responsive to operation of saidsurface pumping means for establishing contact between said 11 fluid andsaid material when such downward movement is arrested.

5. In fluid injection apparatus for a well to which is connected surfacepumping equipment for pumping fluid into said well the combinationcomprising: a compartmented container adapted to be lowered in said wellin said fluid; a gas generating fluid within a first compartment of saidcontainer; a material in a second compartment of said container capableupon contact with said gas generating fluid of causing said fluid togenerate gas within said well; means for arresting movement of saidcontainer downwardly in said well and means responsive to operation ofsaid surface pumping equipment for establishing contact between saidfluid and said mate rial when such downward movement is arrested.

6. Fluid injection apparatus for a well comprising: surface pumpingmeans for pumping fluid into said well; a container adapted to belowered in said well in said fluid; means for arresting movement of saidcontainer downwardly in said well; a gas generating fluid within anupper compartment of said container; a material within a lowercompartment of said container capable upon contact with said gasgenerating fluid of causing said fluid to generate gas; a valve betweensaid compartments responsive to operation of said surface pumping meanswhen said downward movement of said container is orrested to permitpassage of said gas generating fluid from said upper compartment intosaid lower compartment; and gas egress ports in said lower compartmentfor permitting flow of gas from said lower compartment into said well.

7. ln fluid injection apparatus for a well to which is connected surfacepumping equipment for pumping fluid into said well the combinationcomprising: a container adapted to be lowered in said well in saidfluid; means for arresting movement of said container downwardly in saidwell; a gas generating fluid within an upper compartment of saidcontainer; a material within a lower compartment of said containercapable upon contact with said gas generating fluid of causing saidfluid to generate gas; a valve between said compartments responsive tooperation of said surface pumping equipment when said downward movementof said container is arrested to permit passage of said gas generatingfluid from said upper compartment into said lower compartment; and gasegress ports in said lower compartment for permitting flow of said gasfrom said lower compartment into said well.

8. Fluid injection apparatus for a well comprising: surface pumpingmeans for pumping fluid into said well; a lubricator at the surface ofsaid well, said lubricator including a chamber; a container insertablein said chamber for lowering in said well in said fluid; said lubricatorincluding means for releasably holding said container in said chamberand operable to release said container for movement downwardly in saidwell; a gas generating fluid within an upper compartment of saidcontainer; a material within a lower compartment of said containercapable upon contact with said gas generating fluid of causing saidfluid to generate gas; means responsive to operation of said surfacepumping means when downward movement of said container is arrested topermit passage of said gas generating fluid from said upper compartmentinto said lower compartment; and gas egress ports in said lowercompartment for permitting flow of gas from said lower compartment intosaid well.

9. Apparatus for introducing fluid into earth forrnation into or throughwhich a well has been drilled comprising: surface pumping means forpumping fluid into said well; a lubricator at the surface of said well,said lubricator including a chamber; a container insertable in saidchamber for lowering in said well in said fluid responsive to operationof said surface pumping means; said lubricator including means forrelesably holding said container in said chamber and operable to releasesaid container for movement downwardly in said well: a container seatingelement within said well adjacent said earth formation; a gas generatingfluid an upper compartment of said container; a material within a lowercompartment of said container capable upon contact with said gasgenerating fluid of causing said fluid to generate gas; a valve betweensaid compartments. responsive to operation of said surface pumping meansupon seating of said container on said seating element to permit passageof said gas generating fluid from said upper compartment into said lowercompartment; and gas egress ports in said lower compartment forpermitting a flow of gas from said lower compartment into said well.

10. The method of injecting fluid under pressure into earth formationinto which or through which a well has been drilled, comprising: pumpingfluid into the well from the earth surface, disposing a gas generatingmaterial in said well and generating from said material responsive toand during said pumping a volume of gas at a pressure greater thanincipient pressure of the fluid in the well below said surface, andthereby increasing the pressure acting on the fluid and forcing thefluid into said earth formation.

11. The method of introducing fluid under pressure into earth formationinto which or through which a well has been drilled, comprising: pumpingfluid through said well into said earth formation thereby imposingcontinuing hydraulic pumping pressure upon said fluid at the surface ofthe well to displace the fluid into the formation; incrementing saidcontinuing hydraulic pumping pressure upon said fluid by generating aplurality of successive volumes of gas in the fluid being pumped withinthe well adjacent said formation during a series of selected timeintervals responsive to the pumping of fluid through said well into theearth formation while continuing said pumping and maintaining saidhydraulic pump pressure.

12. The method of injecting fluid under pressure into earth formationinto which or through which a well has been drilled, comprising: pumpingfluid into the well from the earth surface; while pumping introducing asecond fluid below said surface capable of gas generation within thewell; inducing responsive to fluid pressure caused by the pumping ofsaid fluid generation of gas by said second fluid during said surfacepumping to increase the pressure acting on said fluid, and implementingthe rate of injection of fluid into said earth formation with said gas.

13. The method of injecting fluid under pressure into earth formationinto which or through which a well has been drilled comprising: pumpingfluid into the well from the earth surface; while pumping introducingwithin said well a second fluid and a material within the well adjacentsaid second fluid capable upon contact therewith to cause said secondfluid to generate gas within said well; continuing such surface pumpingto cause contact between said second fluid and said material responsiveto and during said pumping to generate gas and increase the pressureacting on said fluid thereby implementing the rate of injection of fluidinto said formation with said gas.

14. The method of injecting fluid under pressure into earth formationinto which or through which a well has been drilled comprising: pumpingfluid into the well from the earth surface; while pumping introducinghydrogen peroxide and a material capable upon contact with said hydrogenperoxide to cause decomposition of said hydrogen peroxide to generategas within said well; continuing such surface pumping to cause contactbetween said hydrogen peroxide and said material responsive to andduring said pumping to generate gas and increase the pressure acting onsaid fluid thereby implementing the rate of injection of fluid into saidearth formation.

15. The method of introducing fluid under pressure into earth formationinto or through which a well has been drilled comprising: pumpingfluidthrough the well into said formation from the earth surface; whilepumpin introducin within said well hydrogen eroxide and a materialwithin the well adjacent said hydrogen peroxide capable upon contacttherewith to cause decomposition of said hydrogen peroxide to generategas within said well; continuing such surface pumping to cause contact 1between said hydrogen peroxide and said material responsive to andduring said pumping to generate gas and increase the pressure acting onsaid fluid thereby implementing the rate of injection of fluid into saidearth formation with said gas.

16. The method of injecting fluid under pressure into earth formationinto which or through which a well has been drilled comprising: pumpingfluid into the well from the earth surface; while pumping introducingwithin said well a second fluid and a material capable upon intermixingtherewith to cause said second fluid to generate gas within said well ata rate in proportion to the rate of said intermixing; continuing suchsurface pumping at a selected rate to cause controlled intermixingbetween said second fluid and said material responsive to and duringsaid pumping to generate gas and increase the pressure acting on saidfluid thereby implementing the rate of injection of fluid into saidearth formation with said gas.

17. The method of introducing fluid under pressure into earth formationinto or through which a well has been drilled comprising: pumping fluidthrough the well into said formation from the earth surface; introducingwithin said well a second fluid and a material adjacent said secondfluid capable upon intermixing therewith to cause said second fluid togenerate gas within said well at a rate in proportion to the rate ofsaid intermixing; continuing such surface pumping at a selected rate tocause controlled intermixing between said second fluid and said materialresponsive to and during said pumping to generate gas and implement therate of injection of fluid into said earth formation with said gas.

18. Apparatus for introducing fluid into earth formation into or throughwhich a well has been drilled comprising: surface pumping means forpumping fluid into said well; a container adapted to be lowered in saidwell and positioned adjacent said earth formation; gas generatingmaterial within said container, and fluid pressure operated meansresponsive to the pumping of fluid into said well by said surfacepumping means for causing said material to generate a volume of gasimplementing fluid pressure in said well supplied by said surfacepumping means.

19. Apparatus for introducing fluid into earth formation into or throughwhich a well has been drilled comprising: surface pumping means forpumping fluid into said well;a container; means for supporting saidcontainer in said well adjacent said earth formation; material withinsaid container adapted to generate gas within said well; and fluidpressure operated means for causing said material to generate said gasresponsive to and during operation of said surface pumping means, saidgas implementing fluid pressure in said well supplied by said surfacepumping means.

20. Apparatus for introducing fluid into earth formation into or throughwhich a well has been drilled comprising: surface pumping means forpumping fluid into said well; a container adapted to be lowered in saidwell in said fluid responsive to operation of said surface pumpingmeans; a container seating element within said well adjacent said earthformation; gas generating material within said container; and fluidpressure operated means for causing said material to generate said gasresponsive to and during operation of said surface pumping means uponsaid container seating on said seating element, said gas implementingfluid pressure in said well supplied by said surface pumping means.

21. Apparatus for introducing fluid into earth formation into or throughwhich a well has been drilled comprising: surface pumping means forpumping fluid into said well; a lubricator at the surface of said well;said lubricator including a chamber; a container insertable in saidchamber for lowering in said well in said fluid; said lubricatorincluding means for releasably holding said container in said chamberand operable to release said container for movement downwardly in saidwell; a container seating element within said well adjacent said earthformation; gas generating material within said container, and fluidpressure operated means for causing the generation of gas by saidmaterial upon seating of said container on said seating element.

References Cited in the file of this patent UNITED STATES PATENTS1,806,499 Ranney et a1 May 19, 1931 2,676,662 Ritzmann Apr. 27, 19542,712,355 Hoff July 5, 1955 2,732,016 MacLeod Jan. 24, 1956 2,756,826Ebaugh July 31, 1956 2,766,828 Rach-ford Oct. 16, 1956 2,776,014 Lee etal Jan. 1, 1957 2,781,099 Chesnut Feb. 12, 1957 2,811,209 Elkins Oct.29, 1957

1. THE METHOD OF INTRODUCING FLUID UNDER PRESSURE INTO EARTH FORMATIONINTO OR THROUGH WHICH A WELL HAS BEEN DRILLED COMPRISING: PUMPING FLUIDTHROUGH THE WELL INTO SAID FORMATION FROM THE EARTH SURFACE; DISPOSING AMATERIAL BELOW SAID SURFACE AND ADJACENT SAID FORMATION CAPABLE OF GASGENERATION WITHIN THE WELL; AND INDUCING THE GENERATION OF GAS BY SAIDMATERIAL RESPONSIVE TO AND DURING SAID SURFACE PUMPING TO INCREASE THEPRESSURE ACTING ON THE FLUID AND FORCE THE SAME INTO SAID EARTHFORMATION.